# [Amended]
**AGENCY:**
Federal Aviation Administration (FAA), DOT.
**ACTION:**
Notice of proposed rulemaking (NPRM).
**SUMMARY:**
The FAA proposes to adopt a new airworthiness directive (AD) for certain Honda Aircraft Company LLC (Honda) Model HA-420 airplanes. This proposed AD was prompted by a report of tool damage to multiple locations on the interior fuselage skin fiber and the omission of certain service material from the Airworthiness Limitations Section (ALS) of the maintenance manual. This proposed AD would require incorporating certain material into the ALS of the existing maintenance or inspection program, as applicable. The FAA is proposing this AD to address the unsafe condition on these products.
**DATES:**
The FAA must receive comments on this proposed AD by March 9, 2026.
**ADDRESSES:**
You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:
• *Federal eRulemaking Portal:* Go to *regulations.gov.* Follow the instructions for submitting comments.
• *Fax:* (202) 493-2251.
• *Mail:* U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
• *Hand Delivery:* Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
*AD Docket:* You may examine the AD docket at *regulations.gov* under Docket No. FAA-2026-0020; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this NPRM, any comments received, and other information. The street address for Docket Operations is listed above.
*Material Incorporated by Reference:*
• For Honda Aircraft Company material identified in this proposed AD, contact Honda, 6430 Ballinger Road, Greensboro NC 27410; phone: (336) 662-0246; website: *hondajet.com* .
• You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (817) 222-5110.
**FOR FURTHER INFORMATION CONTACT:**
Kelly Fichter, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (404) 474-5544; email: *[email protected]* .
**SUPPLEMENTARY INFORMATION:**
**Comments Invited**
The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the *ADDRESSES* section. Include “Docket No. FAA-2026-0020; Project Identifier AD-2025-01374-A” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may revise this proposal because of those comments.
Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to *regulations.gov,* including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.
**Confidential Business Information**
CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Kelly Fichter, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
**Background**
The FAA received a report indicating that a quality escape condition (tool damage) was discovered at four locations on the interior fuselage skin fiber at the forward pressure bulkhead ring angle of a Honda Model HA-420 airplane. Additional analysis revealed that the tool damage occurred at the fuselage build stage during the process of removing joint adhesive bead just aft of the forward pressure bulkhead ring angle to facilitate installation of the floor support beams. The tool damage creates local notches in the fuselage skin, which could lead to crack growth. Honda published Honda Aircraft Company Mandatory Service Bulletin (SB) SB-420-53-009, Original Issue, dated April 26, 2023 (Honda Mandatory SB SB-420-53-009), which contains instructions for corrective action to address this unsafe condition. However, Honda Mandatory SB SB-420-53-009 was not included in the ALS of Honda HA-420 Airworthiness Limitations and Inspection Manual, HJ1-29000-013-001, Revision J, dated June 30, 2024. This condition, if not addressed, could cause crack propagation in the skin and result in a pressurization leak and loss of pressurization.
**FAA's Determination**
The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.
**Material Incorporated by Reference Under 1 CFR Part 51**
The FAA reviewed Honda Mandatory SB SB-420-53-009, which specifies serial numbers of affected airplanes, compliance times, and procedures for a visual inspection for defect conditions such as impact damage, burrs, gouges, disbonding, blistering, and discoloration due to heat damage and other surface irregularities. This material also specifies procedures for an ultrasonic inspection of the fuselage skin for damage (local notches, cracks), and repair. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the *ADDRESSES* section.
**Proposed AD Requirements in This NPRM**
This proposed AD would require incorporating Honda Mandatory SB SB-420-53-009 into the ALS of the existing maintenance or inspection program, as applicable.
**Costs of Compliance**
The FAA estimates that this AD, if adopted as proposed, would affect 218 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
| Action | Labor cost | Parts cost | Cost per | Cost on U.S. |
| --- | --- | --- | --- | --- |
| Revise the ALS | 1 work-hour × $85 per hour = $85 | $0 | $85 | $18,530 |
**Authority for This Rulemaking**
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
**Regulatory Findings**
The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify this proposed regulation:
(1) Is not a “significant regulatory action” under Executive Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
**List of Subjects in 14 CFR Part 39**
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
**The Proposed Amendment**
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
**PART 39—AIRWORTHINESS DIRECTIVES**
1. The authority citation for part 39 continues to read as follows:
**Authority:**
49 U.S.C. 106(g), 40113, 44701.
§ 39.13
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
*Honda Aircraft Company LLC:* Docket No. FAA-2026-0020; Project Identifier AD-2025-01374-A.
**(a) Comments Due Date**
The FAA must receive comments on this airworthiness directive (AD) by March 9, 2026.
**(b) Affected ADs**
None.
**(c) Applicability**
This AD applies to Honda Aircraft Company LLC (Honda) Model HA-420 airplanes, serial numbers 42000012 through 42000230, certificated in any category.
**(d) Subject**
Joint Aircraft System Component (JASC) Code 5330, Fuselage Main, Plate/Skin.
**(e) Unsafe Condition**
This AD was prompted by a report of tool damage to multiple locations on the interior fuselage skin fiber at the forward pressure bulkhead ring angle and the omission of certain service material from the Airworthiness Limitations Section (ALS) of the maintenance manual. The FAA is issuing this AD to detect and address tool damage to the interior fuselage skin fiber at the forward pressure bulkhead ring angle. The unsafe condition, if not addressed, could cause crack propagation in the skin and result in a pressurization leak and loss of pressurization.
**(f) Compliance**
Comply with this AD within the compliance times specified, unless already done.
**(g) Required Actions**
(1) Within 30 days after the effective date of this AD, revise the ALS of the existing maintenance manual or instructions for continued airworthiness and your existing approved maintenance or inspection program, as applicable, by incorporating the information specified in Honda Mandatory Service Bulletin SB-420-53-009, Original Issue, dated April 26, 2023.
(2) The initial compliance time for accomplishing the actions specified in Honda Mandatory Service Bulletin SB-420-53-009, Original Issue, dated April 26, 2023, is before accumulating 6,000 total flights or within 30 days after the effective date of this AD, whichever occurs later.
**(h) Provisions for Alternative Actions and Intervals**
After the action required by paragraph (g) of this AD has been done, no alternative actions and associated thresholds and intervals, including life limits, are allowed unless approved as an alternative method of compliance in accordance with the procedures specified in paragraph (i)(1) of this AD.
**(i) Alternative Methods of Compliance (AMOCs)**
(1) The Manager, East Certification Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the East Certification Branch, send it to the attention of the person identified in paragraph (j) of this AD and email to: *[email protected]* .
(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.
**(j) Additional Information**
For more information about this AD, contact Kelly Fichter, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (404) 474-5544; email: *[email protected]* .
**(k) Material Incorporated by Reference**
(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise.
(i) Honda Aircraft Company Mandatory Service Bulletin SB-420-53-009, Original Issue, dated April 26, 2023.
(ii) [Reserved]
(3) For Honda Aircraft Company material identified in this AD, contact Honda Aircraft Company LLC, 6430 Ballinger Road, Greensboro NC 27410; phone: (336) 662-0246; website: *hondajet.com* .
(4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (817) 222-5110.
(5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit *www.archives.gov/federal-register/cfr/ibr-locations* or email *[email protected]* .
Issued on January 20, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.